/*
OpenMVL Matrix Vector Library
Copyright (c) 2009 FluidInteractive (R)
 
This software is provided 'as-is', without any express or implied warranty.
In no event will the authors be held liable for any damages arising
from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it freely,
subject to the following restrictions:
 
1. The origin of this software must not be misrepresented; you must
not claim that you wrote the original software. If you use this
software in a product, an acknowledgment in the product documentation
would be appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must
not be misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
 
Written by: Nicola Candussi <nicola@fluidinteractive.com>
*/

//expr_order.hpp

#ifndef MVL_EXPR_ORDER_HPP
#define MVL_EXPR_ORDER_HPP

#include "expr.hpp"
#include "layout_order.hpp"

namespace mvl {

//change the order of an expression
template<typename NewOrder, typename E>
struct expr_order : public expr<expr_order<NewOrder, E> >
{
public:
    typedef expr_order self_t;

    typedef E expr_t;
    typedef typename expr_t::layout_t expr_layout_t;
    typedef NewOrder new_order;
    typedef typename expr_t::const_closure_t expr_closure_t;

public:

    typedef typename expr_t::value_type     value_type;
    typedef typename layout::layout_order<expr_layout_t, new_order>::type layout_t;
    typedef new_order                       order;
    typedef typename layout_t::Rows         Rows;
    typedef typename layout_t::Cols         Cols;
    typedef typename layout_t::Size         Size;

    typedef const self_t                    const_closure_t;
    typedef const_closure_t                 closure_t;

private:
    typedef typename meta::is_same<typename expr_t::order, new_order>::type is_same_order;
    typedef typename meta::is_same<typename expr_layout_t::tag, layout::dense_layout_tag>::type is_dense_layout;

    template<typename Entry> struct sparse_src { typedef typename Entry::src type; };
    template<typename Entry> struct get_src : meta::eval_if<
        typename meta::or_<is_same_order, is_dense_layout>::type,
        meta::identity<Entry>,
        sparse_src<Entry>
    > {  };

public:
    expr_order(expr_t const& e) : m_e(e) { };

    //access
    template<typename Entry>
    value_type at() const {
        return m_e.template at<typename get_src<Entry>::type>();
    }

private:
    expr_closure_t m_e;
};

template<typename NewOrder, typename E>
struct order_traits
{
    typedef const expr_order<NewOrder, const E> type;
};

template<typename NewOrder, typename E> 
inline 
typename order_traits<NewOrder, E>::type
order(expr<E> const& e) {
    typedef typename order_traits<NewOrder, E>::type expr_t;
    return expr_t(e());
}

} // namespace mvl

#endif
